Hi David,
I'm experimenting using the a scene graph projected in Ortho mode using the
setProjectionMatrixAsOrtho function on the camera and while using the
TerrainManipulator on the camera I noticed that the pan is working, but zoom is
not! In fact, the only way that I could affect any kind of zoom was to narrow
the POV on the camera (that realty is not a zoom).
Well in fact yes... Zoom, in "camera-speak", is making the FOV of the
camera smaller/larger. What the normal manipulators do to zoom is to
move the camera itself, i.e. dolly in/out in "camera-speak". You may
have seen the "dolly in zoom out" effect in movies, where the camera
dollies in while doing a zoom out with the lens at the same time, and I
use that expression to help me remember the difference between the two.
http://en.wikipedia.org/wiki/Dolly_zoom
http://en.wikipedia.org/wiki/File:Contra-zoom_aka_dolly_zoom_animation.gif
But to get back to your question, this is an FAQ... Since with an ortho
camera moving the camera forward or back will have no visible effect
(apart from when you start hitting your near/far planes), you won't be
able to zoom with the normal camera manipulators in an ortho view. You
will have to make your own manipulator or use another way of changing
the camera's left/right and top/bottom clipping planes, effectively the
camera's field of view (though in ortho it's not a frustum, but a box).
I kind of wish (and I've expressed this wish in threads that asked the
same question before, but haven't had time to do anything about it) that
the OSG camera manipulators supported affecting other parameters of the
camera than just its view matrix. As it is, you'll have to affect the
projection matrix yourself directly, i.e. your camera manipulator will
have to know about the camera(s) it's affecting, which defeats the nice
loose coupling that we have between camera manipulator and camera otherwise.
Hope this helps,
J-S
--
______________________________________________________
Jean-Sebastien Guay jean-sebastien.g...@cm-labs.com
http://www.cm-labs.com/
http://whitestar02.webhop.org/
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